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- // SPDX-License-Identifier: GPL-2.0
- /*
- * Copyright (C) 1992 Darren Senn
- */
- /* These are all the functions necessary to implement itimers */
- #include <linux/mm.h>
- #include <linux/interrupt.h>
- #include <linux/syscalls.h>
- #include <linux/time.h>
- #include <linux/sched/signal.h>
- #include <linux/sched/cputime.h>
- #include <linux/posix-timers.h>
- #include <linux/hrtimer.h>
- #include <trace/events/timer.h>
- #include <linux/compat.h>
- #include <linux/uaccess.h>
- /**
- * itimer_get_remtime - get remaining time for the timer
- *
- * @timer: the timer to read
- *
- * Returns the delta between the expiry time and now, which can be
- * less than zero or 1usec for an pending expired timer
- */
- static struct timespec64 itimer_get_remtime(struct hrtimer *timer)
- {
- ktime_t rem = __hrtimer_get_remaining(timer, true);
- /*
- * Racy but safe: if the itimer expires after the above
- * hrtimer_get_remtime() call but before this condition
- * then we return 0 - which is correct.
- */
- if (hrtimer_active(timer)) {
- if (rem <= 0)
- rem = NSEC_PER_USEC;
- } else
- rem = 0;
- return ktime_to_timespec64(rem);
- }
- static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
- struct itimerspec64 *const value)
- {
- u64 val, interval;
- struct cpu_itimer *it = &tsk->signal->it[clock_id];
- spin_lock_irq(&tsk->sighand->siglock);
- val = it->expires;
- interval = it->incr;
- if (val) {
- u64 t, samples[CPUCLOCK_MAX];
- thread_group_sample_cputime(tsk, samples);
- t = samples[clock_id];
- if (val < t)
- /* about to fire */
- val = TICK_NSEC;
- else
- val -= t;
- }
- spin_unlock_irq(&tsk->sighand->siglock);
- value->it_value = ns_to_timespec64(val);
- value->it_interval = ns_to_timespec64(interval);
- }
- static int do_getitimer(int which, struct itimerspec64 *value)
- {
- struct task_struct *tsk = current;
- switch (which) {
- case ITIMER_REAL:
- spin_lock_irq(&tsk->sighand->siglock);
- value->it_value = itimer_get_remtime(&tsk->signal->real_timer);
- value->it_interval =
- ktime_to_timespec64(tsk->signal->it_real_incr);
- spin_unlock_irq(&tsk->sighand->siglock);
- break;
- case ITIMER_VIRTUAL:
- get_cpu_itimer(tsk, CPUCLOCK_VIRT, value);
- break;
- case ITIMER_PROF:
- get_cpu_itimer(tsk, CPUCLOCK_PROF, value);
- break;
- default:
- return(-EINVAL);
- }
- return 0;
- }
- static int put_itimerval(struct __kernel_old_itimerval __user *o,
- const struct itimerspec64 *i)
- {
- struct __kernel_old_itimerval v;
- v.it_interval.tv_sec = i->it_interval.tv_sec;
- v.it_interval.tv_usec = i->it_interval.tv_nsec / NSEC_PER_USEC;
- v.it_value.tv_sec = i->it_value.tv_sec;
- v.it_value.tv_usec = i->it_value.tv_nsec / NSEC_PER_USEC;
- return copy_to_user(o, &v, sizeof(struct __kernel_old_itimerval)) ? -EFAULT : 0;
- }
- SYSCALL_DEFINE2(getitimer, int, which, struct __kernel_old_itimerval __user *, value)
- {
- struct itimerspec64 get_buffer;
- int error = do_getitimer(which, &get_buffer);
- if (!error && put_itimerval(value, &get_buffer))
- error = -EFAULT;
- return error;
- }
- #if defined(CONFIG_COMPAT) || defined(CONFIG_ALPHA)
- struct old_itimerval32 {
- struct old_timeval32 it_interval;
- struct old_timeval32 it_value;
- };
- static int put_old_itimerval32(struct old_itimerval32 __user *o,
- const struct itimerspec64 *i)
- {
- struct old_itimerval32 v32;
- v32.it_interval.tv_sec = i->it_interval.tv_sec;
- v32.it_interval.tv_usec = i->it_interval.tv_nsec / NSEC_PER_USEC;
- v32.it_value.tv_sec = i->it_value.tv_sec;
- v32.it_value.tv_usec = i->it_value.tv_nsec / NSEC_PER_USEC;
- return copy_to_user(o, &v32, sizeof(struct old_itimerval32)) ? -EFAULT : 0;
- }
- COMPAT_SYSCALL_DEFINE2(getitimer, int, which,
- struct old_itimerval32 __user *, value)
- {
- struct itimerspec64 get_buffer;
- int error = do_getitimer(which, &get_buffer);
- if (!error && put_old_itimerval32(value, &get_buffer))
- error = -EFAULT;
- return error;
- }
- #endif
- /*
- * The timer is automagically restarted, when interval != 0
- */
- enum hrtimer_restart it_real_fn(struct hrtimer *timer)
- {
- struct signal_struct *sig =
- container_of(timer, struct signal_struct, real_timer);
- struct pid *leader_pid = sig->pids[PIDTYPE_TGID];
- trace_itimer_expire(ITIMER_REAL, leader_pid, 0);
- kill_pid_info(SIGALRM, SEND_SIG_PRIV, leader_pid);
- return HRTIMER_NORESTART;
- }
- static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
- const struct itimerspec64 *const value,
- struct itimerspec64 *const ovalue)
- {
- u64 oval, nval, ointerval, ninterval;
- struct cpu_itimer *it = &tsk->signal->it[clock_id];
- nval = timespec64_to_ns(&value->it_value);
- ninterval = timespec64_to_ns(&value->it_interval);
- spin_lock_irq(&tsk->sighand->siglock);
- oval = it->expires;
- ointerval = it->incr;
- if (oval || nval) {
- if (nval > 0)
- nval += TICK_NSEC;
- set_process_cpu_timer(tsk, clock_id, &nval, &oval);
- }
- it->expires = nval;
- it->incr = ninterval;
- trace_itimer_state(clock_id == CPUCLOCK_VIRT ?
- ITIMER_VIRTUAL : ITIMER_PROF, value, nval);
- spin_unlock_irq(&tsk->sighand->siglock);
- if (ovalue) {
- ovalue->it_value = ns_to_timespec64(oval);
- ovalue->it_interval = ns_to_timespec64(ointerval);
- }
- }
- /*
- * Returns true if the timeval is in canonical form
- */
- #define timeval_valid(t) \
- (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC))
- static int do_setitimer(int which, struct itimerspec64 *value,
- struct itimerspec64 *ovalue)
- {
- struct task_struct *tsk = current;
- struct hrtimer *timer;
- ktime_t expires;
- switch (which) {
- case ITIMER_REAL:
- again:
- spin_lock_irq(&tsk->sighand->siglock);
- timer = &tsk->signal->real_timer;
- if (ovalue) {
- ovalue->it_value = itimer_get_remtime(timer);
- ovalue->it_interval
- = ktime_to_timespec64(tsk->signal->it_real_incr);
- }
- /* We are sharing ->siglock with it_real_fn() */
- if (hrtimer_try_to_cancel(timer) < 0) {
- spin_unlock_irq(&tsk->sighand->siglock);
- hrtimer_cancel_wait_running(timer);
- goto again;
- }
- expires = timespec64_to_ktime(value->it_value);
- if (expires != 0) {
- tsk->signal->it_real_incr =
- timespec64_to_ktime(value->it_interval);
- hrtimer_start(timer, expires, HRTIMER_MODE_REL);
- } else
- tsk->signal->it_real_incr = 0;
- trace_itimer_state(ITIMER_REAL, value, 0);
- spin_unlock_irq(&tsk->sighand->siglock);
- break;
- case ITIMER_VIRTUAL:
- set_cpu_itimer(tsk, CPUCLOCK_VIRT, value, ovalue);
- break;
- case ITIMER_PROF:
- set_cpu_itimer(tsk, CPUCLOCK_PROF, value, ovalue);
- break;
- default:
- return -EINVAL;
- }
- return 0;
- }
- #ifdef CONFIG_SECURITY_SELINUX
- void clear_itimer(void)
- {
- struct itimerspec64 v = {};
- int i;
- for (i = 0; i < 3; i++)
- do_setitimer(i, &v, NULL);
- }
- #endif
- #ifdef __ARCH_WANT_SYS_ALARM
- /**
- * alarm_setitimer - set alarm in seconds
- *
- * @seconds: number of seconds until alarm
- * 0 disables the alarm
- *
- * Returns the remaining time in seconds of a pending timer or 0 when
- * the timer is not active.
- *
- * On 32 bit machines the seconds value is limited to (INT_MAX/2) to avoid
- * negative timeval settings which would cause immediate expiry.
- */
- static unsigned int alarm_setitimer(unsigned int seconds)
- {
- struct itimerspec64 it_new, it_old;
- #if BITS_PER_LONG < 64
- if (seconds > INT_MAX)
- seconds = INT_MAX;
- #endif
- it_new.it_value.tv_sec = seconds;
- it_new.it_value.tv_nsec = 0;
- it_new.it_interval.tv_sec = it_new.it_interval.tv_nsec = 0;
- do_setitimer(ITIMER_REAL, &it_new, &it_old);
- /*
- * We can't return 0 if we have an alarm pending ... And we'd
- * better return too much than too little anyway
- */
- if ((!it_old.it_value.tv_sec && it_old.it_value.tv_nsec) ||
- it_old.it_value.tv_nsec >= (NSEC_PER_SEC / 2))
- it_old.it_value.tv_sec++;
- return it_old.it_value.tv_sec;
- }
- /*
- * For backwards compatibility? This can be done in libc so Alpha
- * and all newer ports shouldn't need it.
- */
- SYSCALL_DEFINE1(alarm, unsigned int, seconds)
- {
- return alarm_setitimer(seconds);
- }
- #endif
- static int get_itimerval(struct itimerspec64 *o, const struct __kernel_old_itimerval __user *i)
- {
- struct __kernel_old_itimerval v;
- if (copy_from_user(&v, i, sizeof(struct __kernel_old_itimerval)))
- return -EFAULT;
- /* Validate the timevals in value. */
- if (!timeval_valid(&v.it_value) ||
- !timeval_valid(&v.it_interval))
- return -EINVAL;
- o->it_interval.tv_sec = v.it_interval.tv_sec;
- o->it_interval.tv_nsec = v.it_interval.tv_usec * NSEC_PER_USEC;
- o->it_value.tv_sec = v.it_value.tv_sec;
- o->it_value.tv_nsec = v.it_value.tv_usec * NSEC_PER_USEC;
- return 0;
- }
- SYSCALL_DEFINE3(setitimer, int, which, struct __kernel_old_itimerval __user *, value,
- struct __kernel_old_itimerval __user *, ovalue)
- {
- struct itimerspec64 set_buffer, get_buffer;
- int error;
- if (value) {
- error = get_itimerval(&set_buffer, value);
- if (error)
- return error;
- } else {
- memset(&set_buffer, 0, sizeof(set_buffer));
- printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
- " Misfeature support will be removed\n",
- current->comm);
- }
- error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
- if (error || !ovalue)
- return error;
- if (put_itimerval(ovalue, &get_buffer))
- return -EFAULT;
- return 0;
- }
- #if defined(CONFIG_COMPAT) || defined(CONFIG_ALPHA)
- static int get_old_itimerval32(struct itimerspec64 *o, const struct old_itimerval32 __user *i)
- {
- struct old_itimerval32 v32;
- if (copy_from_user(&v32, i, sizeof(struct old_itimerval32)))
- return -EFAULT;
- /* Validate the timevals in value. */
- if (!timeval_valid(&v32.it_value) ||
- !timeval_valid(&v32.it_interval))
- return -EINVAL;
- o->it_interval.tv_sec = v32.it_interval.tv_sec;
- o->it_interval.tv_nsec = v32.it_interval.tv_usec * NSEC_PER_USEC;
- o->it_value.tv_sec = v32.it_value.tv_sec;
- o->it_value.tv_nsec = v32.it_value.tv_usec * NSEC_PER_USEC;
- return 0;
- }
- COMPAT_SYSCALL_DEFINE3(setitimer, int, which,
- struct old_itimerval32 __user *, value,
- struct old_itimerval32 __user *, ovalue)
- {
- struct itimerspec64 set_buffer, get_buffer;
- int error;
- if (value) {
- error = get_old_itimerval32(&set_buffer, value);
- if (error)
- return error;
- } else {
- memset(&set_buffer, 0, sizeof(set_buffer));
- printk_once(KERN_WARNING "%s calls setitimer() with new_value NULL pointer."
- " Misfeature support will be removed\n",
- current->comm);
- }
- error = do_setitimer(which, &set_buffer, ovalue ? &get_buffer : NULL);
- if (error || !ovalue)
- return error;
- if (put_old_itimerval32(ovalue, &get_buffer))
- return -EFAULT;
- return 0;
- }
- #endif
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